ISO 20958 pdf download

ISO 20958 pdf download Condition monitoring and diagnostics of machine systems — Electrical signature analysis of three-phase induction motors
Scope
This International Standard sets out guidelines for the online techniques recommended for the purposesof condition monitoring and diagnostics of machines, based on electrical signature analysis. Thisnternational Standard is applicable to three-phase induction motors.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and areindispensable for its application. For dated references, only the edition cited applies. For undatedreferences, the latest edition of the referenced document (including any amendments) applies.ISO 13372, Condition monitoring and diagnostics ofmachines – Vocabulary
3 Terms and definitions
For the purposes ofthis document, the terms and definitions given in ISO 13372 and the following apply.31
current analysisanalysis of the three supply currents to a motor for magnitude, balance, and harmonic content
3.2
current signature analysisspectral analysis performed on the line current to the motor to determine ifthere are currents at specificfrequencies that can indicate component defects
Note 1 to entry: Traditionallv. this has been focused on a single phase. but newer techniaues such as Park’s vectotand voltage and current systems that analyse all three phases simultaneously can provide additional information.
3.3
induction motor
asynchronous AC machine that comprises a magnetic circuit interlinked with two electric circuits orsets ofcircuits rotating with respect to each other and in which power is transferred from one circuit toanother by electromagnetic induction
Note 1 to entry: There are two basic types: squirrel-cage (SCI) and wound-rotor induction motors.
3.4
squirrel-cage induction motorinduction motor in which the secondary circuit consists of usually un-insulated rotor bars in core slotsshorted together by end rings connected to both ends of each bar
Note 1 to entry:The most common bar and end ring materials are copper, aluminium, or alloys ofthese materials
4 Electrical signature analysis of three-phase induction motors
4.1 General
The vast majority of motors used in industry are induction machines.
Reliability surveys show that the most vulnerable parts of an induction motor are the bearings, the stator winding and core pack, and the rotor cage winding.
There is a lot of published material about a group of monitoring and diagnostic techniques, collectively referred to as electrical signature analysis, that can be used for condition monitoring of induction motors. In general, these techniques are based on the analysis either of signals available at the motor terminals or obtained through appropriate transducers fitted to the structure. Several of these techniques are presented in 4.2 to 4.8.